This is a project that my eight-year-old daughter, MH, and I have had a lot of fun working on. She has bricked a kindle fire and was sort of reaching the limits of her ipad and it seemed like this would be a fun project. Before this she has spent some time playing with circuits, tinkering with a raspberry pi, playing with tinkercad and 3d printing, and so on, and a while ago we had cannibalized parts from three old laptops for parts to make one working one. So that is a bit of previous experience that helped prepare her.
We are aiming for a tablet that can play some games, watch some movies and netflix, connect to the web and do some basic kid coding and homework sorts of sites. I wanted it to be simple enough for her to put together without soldering or cutting circuit boards, etc.
We hope that our project gives you some ideas for your own project.
Step 1: Print and Gather the Parts
We used an odroid c2 as the single board computer, basically because it has (as MH says) more "oompf" than a raspberry pi (It has 2 gigs of ram). The following parts were necessary, all available from www.ameridroid.com:
Odroid C2 SBC
VU-7 touchscreen - this screen comes with handy hdmi and microsd connectors
An emmc and/or sd card
A power cable
Next you will need to print a case. We used an edit of the ameridroid plan located here: http://respectech.com/odroid/files/3d/vu7-tablet/...
MH made a few changes in tinkercad, basically to allow for adding an external battery by cutting the back in half and personalizing it. You can find our 3d print files here: http://www.thingiverse.com/thing:1680891
You can purchase a version already printed out directly from Ameridroid here http://ameridroid.com/products/ameridroid-vu7-tablet-kit
Finally, there other things you could add if you want - if you tinker around with stuff you probably have some sorts of things like these around. We are adding an external battery, sound card, usb wi-fi dongle, and an snes controller.
Step 2: Put the Pieces Together
A tip for parents - put a dry run through of this together the night before and make sure it is working before you turn it over to your kid to really put together. You are going to probably make some changes to the android boot.ini and build.prop file to set the resolution on the monitor. I also ended up making some on the fly pocket knife "engineering" on the case.
The first thing is set up your memory card. You can use either an emmc or micro sd card or both. If you have both, it will boot from the emmc and use the sdcard as storage. You probably already have an sd card, but an emmc card will be better performance. I went ahead and got MH an emmc card and Android is installed. I used a micro sd/emmc adapter to connect to the emmc to a pc to edit the boot.ini and build.prop, and went ahead and installed a market and some apk also. For the SD card, we used one that was already filled with movies and I added some roms, etc. Go ahead and and load that card up because it will be on the board and not easy to access once you put it together. The emmc connects to the odroid c2 in a very small connector so be careful fitting this and you may need to do it for little hands. The sd card is an easy slide in. You'll want both connected before assembling further.
Connect the screen and power and make sure everything is working the way you want before further assembly. Then lay the screen in the top frame and insert three 1.5" screws through the front of the frame and lower the c2 on to them, use the metal spacers that came with the vu7 between the screen and the c2, and the printed spacers above. We had 1.25" screws and later figured out we would need longer ones.
Insert the hdmi and micro sd connector boards between the c2 and the vu7, you have to thread this through the printed side.
For the short side, use smaller screws, we used one half inch. We used super glue on the short side also because the screen only had two corner holes.
To connect the external battery, we used velcro attached to the battery and the short side. This means that a usb power cable is running from the battery to the C2 power, and from there also powering the screen through the microsd connector to the screen. This is a less elegant solution than using an internal battery and a power connector, but it has some advantages here. For one, you may already have an external battery laying around and even if you don't it will be cheaper and you'll get more power if you just buy an external battery from amazon.com than to buy a battery and a control circuit for it. Also, this means a child can put it together with no soldering and the power switch is already built in. Also, it will be easy to use for something else in the future. Finally, because we had a "solar power" external battery there's that. In all, it gives it a sort of cool hackyness
Step 3: Get It Up and Running
We started with #4 1.25" screws and they were too short. We picked up some #6 2" screws and they were too long. So I think that 1.5" would be just right. You will put the screw through the front frame, the screen, then the mother board then one of the printed spacers then the back cover then a nut. The #6 were really good and snug going through the holes in the screen and the c2 board. I figured that was a good thing.
We had a usb audio jack, and our original plan was to tuck it in the bottom but that wasn't going to fit, so at this point there is some fiddling to figure out how to fit that. I used a pocket knife to cut a hole in the top side and ran the cable down the inside from there.
We used velcro to put on the battery.
At that point, boot it up.
If you are using a game controller plug it in and play a game.
MH has named hers "Frankentab" from all the screws and parts sticking out.
Have fun with your project!